The systems for administering intervenous fluids to patients now generally include a control circuitry to assure the delivery of the proper amount of liquid. To make this determination, the control system often includes some manner of ascertaining the actual amount of fluid received by the patient. Generally, to make this determination, the control system will include a drop detector to actually count the number of drops of fluid flowing from the bottle of I.V. solution. The rate of drops passing through a drip chamber effectively provides knowledge as to the amount of solution passing into the patient.
The determination that a drop has indeed fallen through the drip chamber generally involves the passage of a beam of electromagnetic (em.) radiation through the chamber. The passage of the drop disturbs the beam of radiation which the control circuitry then attempts to determine.
However, control circuits utilizing radiation to determine the passage of a drops suffers from the ubitiquous presence of radiation of almost all wavelengths in the area of the drip chamber. Virtually any source of light will interfere with the determination of the number of drops.
Thus, such control systems generally make extensive efforts to shield the drip chamber from any source of ambient light. This entails additional expense to place the drip chamber in substantially total darkness (aside from the radiation used to determine a drop).
However, a drop passing through the beam of radiation often does not effectuate a major disturbance of that beam. Thus, even minimal amounts of ambient light can seriously interfere with the proper determination. Moreover, should an attendant attempt to make sure that the fluid flows from the bottle to the patient, opening the door of the device can add so much light as to seriously disrupt the determination. At night, the attendant may have to use a flashlight to make the visual determination. In a darkened room, the light from such a source will, even under the most desirable circumstances, often create a false reading.
Accordingly, the search continues for a system that will result in the reliable determination of the amount of I.V. fluid flowing to a patient. The system should generally display very little, if any, suseptibility to disruption by ambient light.